Prestressed reinforced concrete floor beam



March 17, 1953 J. c. H. LACHAISE PRESTRESSED REINFORCED CONCRETE FLOOR BEAM Filed Oct. 15, 1945 Patented Mar. 17, 1953 OFFICE PRESTRESSED REINFORCED CONCRETE FLOOR BEAM Jean Celestin Hippolyte Lachaisc, Vitry-sur-Seine, France Application October 13, 1945, Serial No. 622,128 In France July 6, 1943 Section 1, Public Law 690, August 8, 1946 Patent expires July 6, 1963 3 Claims. 1

The object of the present invention is a prestressed reinforced concrete floor, which is particularly characterized by very great lightness and strength. Another object of this invention is a beam designed for the manufacture of said floor, which can easily be manufactured by quantity production and is consequently inexpensive; a number of such beams may be assembled in a very simple manner to constitute a floor of any size. This invention is also concerned with processes for the manufacture of said floor and beams.

The beam according to this invention is made of concrete or like material, and is g ven substantially on the whole, an I cross-section, and two metal rods at least, set in tension, are disposed near its end faces, means being provided to impart to the beam the compression stresses from the said rods. The substantially if not formally I cross-sections of the beam can be obtained by making up a twin-beam; th two elementary beams constituting the said twinbeam are each given substantially a u crosssection and are fastened together in a Way to impart to the beam proper the compression stresses from the above mentioned rods.

According to a first embodiment of the invention, the beam comprises two elementary beams of U cross-section which are disposed so that their bottoms are opposite each other; two metal rods, under tension, are placed between said bottoms, preferably one near the upper and the other near the lower wings of the elementary beams. Said Wings compose the upper and. lower faces of the floor. Advantageously, the bottoms of the elementary beams are spaced apart, the distance being sufficient to enable pouring concrete between them and the metal rods, whatever the diameter of the latter is.

In all embodiments, at the. end of each beam is disposed a counter-plate, such as a metal plate, on which the metallic rods are anchored, said plate distributing the stresses onto the wholemass of concrete.

In all the embodiments above described, use is made of elementary beams the Winds of which are not particularly thick, and, preferably, said thickness decreases from the bottom of the beam up to its longitudinal edge. It is consequently advantageous to provide, at convenient intervals, cross-partitions which are moulded together with the beam. They act as sustainers for the wings which, otherwise, would be too sensitive to collisions, and simultaneously as stifleners to avoid warping of the beam. In or- 2 der to facilitate the subsequent joining of the beams, which are disposed side by side to form the floor, each beam may be formed so that one of the cross-partitions is off-set with respect to the longitudinal edge of the wing, the offset or outwardly projecting partition portion fitting into the adjacent beam. In this manner, the adjacent beams fit one in the other and constitute a whole.

Other characteristics of the present invention will appear from the following detailed description of some embodiments thereof together with the accompanying drawings given merely by way of non-limitative example, and in which:

Fig. 1 is a partial cross-section of a floor according to the invention;

Fig. 2 is an isometric view of a beam built up by joining two elementary beams;

Fig. 3 is a View similar to Fig. 2 but showing a modified form of end member.

Referring now to the drawings, in which like reference numerals denote similar elements, a section of a typical floor constructed from beams which form the invention is illustrated, the floor being constituted by a plurality of concrete beams, such as those indicated by reference numerals l and 2, disposed side by side. Prelerably the upper wings, such as wings 3 and l, and wings a and ii, of adiacent beams are n contact, as may be accomplished with the construction shown in 3, and so likewise should be together the lower wings ta, 3a, and 5a, to. Each beam such as I and 2 is constituted, in embodiment, by two elementary beams l and 8, which are disposed opposite each other, their wings being diver ent and approximately horizontal. Said elementary beams are of u crosssection; their bottoms s and [8 are uniformly distant one from the other, said distance bein such that, regardless of the diameter of rods ll--l2', there remains, between the latter and the bottoms 9, ill a space which is sunicient to allow for the easy introduction of the filling con crete l3.

As shown on Fig. 2, cross-partitions or plates M are spaced from each other in the elementary beam so as to stilfen the same. and sustain the wings 5 and 5a. Figs. 1 and 2 show a partition plate it projecting outwardly beyond the longitudinal edges of the wings of one beam, and the: partition plate in the other beam which aligns with this plateis accordingly shortened. As shown in Figurell, the partition it protrudes from the longitudinal edge of the elementary beam 5 and the opposite partition 14 has its edge recessed with respect to the longitudinal edge of the elementary beam 6. By way of example, five cross-partitions may be provided for each elementary beam. At their end, the elementary beams 1 and 8, constituting the beam proper, are capped by a counterplate l which supports the rods II and i2 and distributes on the elementary beams 7, 8 the compression stresses transmitted by Said rods. As shown in Fig. 2, counterplate I5 is in the nature of a box enclosing the end of the elementary beam; the wings N5, of the counterplat respectively overlying and underlying the upper and lower wings 3, 5 and 3a, 5a of the beam ends and the wings 20, of the counterplate completing the encasement of the beam ends. In this embodiment, counterplate I5 distributes the compression stresses transmitted by rods II and 12 over the entire end surfaces of the beams i, 8 and, in addition, the counterplate wings l6, l6 and E0, 20 predetermine that the beams will be precisely positioned and spaced with respect to one another.

The ends of rods H, l2 are, preferably, threaded and the rods are placed under tension by screwing nuts I7 on the ends. It is however understood that use may be made of any desired process for anchoring or placing the rods I 1', 12 under tension.

The embodiment shown in Fig. 3 is identical to the one shown in Fig. 2 except in that counterplate 15a is U-shaped in cross section, and has only the arms 1611 which bracket the ends of beams 7 and 8.

The beams are in each instance provided with the cross-partitions I4 above described, whatever the embodiment may be.

The construction of a floor by using the above described beams is effected by placing sid by side the desired number or" these beams and then spreading a coating material over the surface of the floor so obtained. The cross-partions is secure the joining of the beams by reason of their being fitted between the wings.

There may be manufactured in a plant, either the elementary beams which are afterwards assembled on the ground and the rods which are placed under tension before pouring concrete in the free intervals, or the beam proper, the concrete being poured only when the floor is built up. These operations may also be performed on the ground.

It will be understood that the concrete Which is poured about the rods is particularly intended to protect these rods against corrosion. Instead of concrete a suitable filling material may be used, or the rods may be coated with an anticorrosion product. It is also possible to place the rods under tension after the setting of the beams side by side and dispose a single counterplate on each side of the floor for all of the beams.

What I claim is:

1. A beam which comprises a composite fabrication including, in combination, two elongate continuous beam elements disposed parallel to and closely spaced from on another, clamping means disposed at each end of said elements and having substantially a U cross-section, the respective ends of the two elements being disposed within the clamping means of substantially U-shaped cross section, the corresponding' extremities of the two elements abutting the web of one of said clamping means and the flanges of said clamping means overlying and snugly engaging the surfaces of the two corresponding element ends, and metal rods set in tension and anchored on said clamping means so as to force them one towards the other, said metal rods being disposed between said two elements.

2. A beam which comprises a composite fabrication including, in combination, two elementary beams of substantially U-cross-section disposed back to back with their backs closely spaced from one another, said beams each having divergent wings, cross-partitions provided in each elementary beam between its wings, one of said cross-partitions being off-set inwardly with respect to the free edges of the wings and the following cross partition projecting the same amount outwardly with respect to the free edge of the wings, a substantially rectangular boxshaped clamping means having an open side therein disposed at each extremity of the composite beam with the corresponding ends of the two elementary beams extending through the said open side and disposed within the boxshaped clamping means and abutting the base thereof, the walls of the clamping means surrounding and snugly engaging th surfaces of the two corresponding elementary beam ends, and metal rods set in tension and anchored on said clamping means so as to force them one towards the other, said metal rods being disposed between said two elementary beams.

3. A preformed beam designed to b delivered as a unit to the place where it is to be used, said beam comprising two elementary U beams of elongate unitary form with the bottoms of the Us arranged opposite to and spaced from each other, a box-like end member for each end of the elementary beams, each end membe enclosing the adjacent ends of both beams and predetermining the positioning of same, and metal rods disposed in the space between the elementary beams, anchored to said end members and tensioned to force the end members toward each other.

JEAN CELESTIN I-HPPOLYTE LACI-IAISE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re. 11,356 Lee Aug. 8, 1893 233,029 Schillinger Oct. 5, 1380 161,028 Lee Oct. 13, 1891 1,028,573 Lund June 4, 1912 1,148,228 Higgins July 27, 1915 1,891,597 Jagdmann Dec. 20, 1932 2,044,382 Dunagan June 16. 1936 FOREIGN PATENTS Number Country Date 2,416 Great Britain 1896 499,076 France Jan. 30, 1920 143,632 Great Britain May 26, 1920 601,784 France Dec. 10, 1925 133,732 Switzerland Aug. 16, 1929 691,783 France July 21, 1930 330,117 Italy 1935 556,572 Great Britain Oct. 11, 1943 

